Esters of tall oil pitch and polyoxyethylene compounds and their use as drilling fluid additives



United States Patent Office US. Cl. 252-8.5 Claims ABSTRACT OF THEDISCLOSURE Esters useful as drilling mud additives for oil base andaqueous base drilling muds are formed by heating a mixture of tall oilpitch and a polyoxyethylene compound under conditions of reflux forabout 1 to 3 hours or at a temperature in the range of about 130280 C.for about 1 to 3 hours at about atmospheric pressure.

This application is a division of my copending application Ser. No.413,316 filed Nov. 23, 1964 now Patent No. 3,379,708, which is acontinuation-in-part of application Ser. No. 330,586 filed Dec. 16,1963, now abandoned.

This invention relates to drilling fluids. In one aspect it relates todrilling fluids such as aqueous, oil-base, and emulsion types ofdrilling fluids used in drilling deep wells such as oil and gas wells.In another aspect it relates to a method for preparing and using asimple drilling fluid which exhibits low fluid loss properties and otherdesirable rheological properties in illitic clay drilling fluid systems.Inanother aspect it relates to a flocculant for bentonitic clays. Instill another aspect the invention relates to a novel composition ofmatter which has particular utility as a drilling fluid additive.

It is well known that in perforating the earthen forma tions to tapsubterranean deposits such as gas or oil, the perforation isaccomplished by well drilling tools and a drill fluid. The drillingfluid serves to cool and lubricate the drill bit, to carry the cuttingsto the surface as the drilling fluid is circulated in and out of thewell, to support at least part of the weight of the drill pipe and drillbit,- to provide a hydrostatic pressure head to prevent caving of thewalls of the well bore, to deposit on the surface of the well bore afilter cake which acts as a thin, semi-impervious layer to prevent unduepassage therethrough of fluids, and to perform other functions as arewell known in the drilling art.

It is important that the drilling fluid exhibit a relatively low rate offiltration or fluid loss in addition to having desirable rheologicalproperties such as viscosity and gel strengths. It is also importantthat the drill fluid system should be kept as simple and inexpensive aspossible in order to avoid undue expense in the drilling of a well.

It is therefore an object of this invention to provide an illitic claybase drilling fluid having low fluid loss characteristics. It is also anobject of this invention to provide a novel composition of matter whichis useful as a drilling fluid additive. Still another object of theinvention is to provide a method for controlling the fluid lossproperties of an illitic clay base drilling fluid without adverselyaffecting the rheological properties of the drilling fluid. Stillanother object is to provide a flocculant for hydrophilic bentoniticclays and a dispersant for organophilic bentonitic clays. Still anotherobject is to provide a drilling or well-working fluid which is effectivein drilling fluids contaminated with salts such as sodium chloride and3,461,068 Patented Aug. 12, 1969 calcium sulfate as well as beingelfective in drilling fluids wherein these contaminating salts areabsent. Still another object is to provide an additive for oil basedrilling fluids containing organophilic bentonitic clays. The provisionof a concentrate to facilitate preparation of an oil base drilling fluidin the field is yet another object of the invention. Further objects andadvantages of this invention will become apparent to those skilled inthe art after studying the disclosure of the invention including thedetailed description of the invention.

Broadly, the invention contemplates a novel composition of matterprepared by reacting tall oil pitch with a polyethylene glycol or with amono-ether or mono-ester of a polyethylene glycol. Such reaction productis an ester which can be represented by the formula wherein n is aninteger of 4 to 500, R contains 0 to carbon atoms and is selected fromthe group consisting of hydrogen and alkyl, aryl, alkaryl, aralkyl,cycloalkyl, cycloalkylalkyl, alkylcycloalkyl and acyl radicals, and R isan acyl radical from an acid constituent of tall oil pitch.

Some examples of applicable esters are those prepared by esterificationof tall oil pitch with polyoxyethylene compounds of the general formulawhere n is 4-500, preferably 6-100, and R is hydrogen, methyl, ethyl,isopropyl, isobutyl, hexyl, octyl, dodecyl, octadecyl, triacontyl,hexacontyl, phenyl, l-naphthyl, otolyl, m-ethylphenyl, m-hexylphenyl,o-octylphenyl, pisooctylphenyl, p-nonylphenyl, o-decylphenyl,m-octadecylphenyl, benzyl, Z-phenyloctyl, cyclohexyl,3-cyclohexylpropyl, 3-methylcyclopentyl, acetyl, propionyl, lauroyl,stearoyl, and the like; The nonylphenyl derivatives, e.g.,p-nonylphenoxypoly(ethyleneoxy) ethanol, in which n has a value of6-100, are especially good.

The additives can be utilized in Water-base drilling fluids containingillitic clays to reduce the fluid loss properties of the drilling fluidwithout appreciably affecting the rheological properties of the drillingfluid. Esters of tall oil pitch and polyoxyethylated nonylphenols areespecially effective as fluid loss control additives in such water-basefluids and are particularly useful in low solids, illiticclay-containing water-base fluids containing salt (sodium chloride) andgypsium or anhydrite (calcium sulfate), where fluid loss control isoften diflicult to obtain.

The additives can also be utilized in oil-base drilling fluidscontaining organophilic bentonitic clays (Bentones) to increaseviscosity particularly when polar compounds such as sulfonated asphaltare added to the drilling fluid for fluid loss control. When about 2 to3 pounds per barrel of the tall oil pitch ester is added to an oil-basedrilling fluid containing sulfonated asphalt, the viscosity of thesystem is raised sufliciently to maintain weighting material such asbarite in suspension without appreciably affecting the fluid losscontrol provided by the addition of the sulfonated asphalt.

The additives of the invention are flocculants for bentonitic clays inwater-base systems and therefore are useful for rejecing bentoniticclays from drilling fluids and are useful for drilling throughbentonitic clay formations with Water-base drilling fluids.

Although the concentration of the additive for fluid loss control inillitic clay systems can vary over a wide range, it will usually bemaintained in the range of about 4 to 20 pounds of additive per barrelof drilling fluid and the concentration will preferably be maintainedbetween about 6 and 10 pounds of additive per barrel of drilling fluid.

The aqueous drilling fluids of this invention need contain only waterand a finely-divided illitic clay; however, it is within the scope ofthis invention to incorporate the novel fluid loss additive into adrilling fluid containing other additives or to add other materials,except bentonitic clays, to the drilling fluid containing the novelfluid loss additive.

The addition of the composition of the invention in Bentone-containing,oil-base drilling fluid systems for viscosifying such drilling fluidwill usually be at least an amount equal to that of the polar compoundthat was added to control fluid loss Often a small amount of thecomposition, e.g., about 2-3 pounds per barrel of fluid, will increasethe viscosity and gel strengths of an oil-base fluid system suflicientlyto suspend the necessary or desired amount of weighting agent. Whenrelatively large amounts of weighting agent,are to be added to thesystem, it may be desirable to add as much as 20 to 30 pounds of thecomposition per barrel of drilling fluid.

In the preparation of oil-base drilling fluids containing Bentones it isessential that the Bentones be dispersed completely in the system so asto obtain maximum viscosity rapidly. Rapid dispersion of Bentones in oilrequires a milling operation utilizing a mill such as a paint mill orcolloid mill and a dispersion agent. The rapid preparation of suchdispersion in the field with normal drilling fluid mixing equipment isdiflicult if not impossible.

I have found that the tall oil pitch esters of the invention can beutilized in the preparation of Bentone-containing oil base drillingfluids and that a concentrate of Bentone and oil can be prepared at aconvenient location and shipped as a grease-like solid to the drillingsite where it can be mixed with oil utilizing normal drilling fluidmixing equipment to produce an oil-base drilling fluid of desiredviscosity. The tall oil pitch ester performs as a viscosifier for theBentone-containing oil base drilling fluid as well as a dispersion agentfor dispersing the Bentone in the oil.

Bentones are organophilic bentonite clays. The treatment of Bentoniteclay to produce a Bentone is well known.

4 EXAMPLE I Esters for use as drilling mud additives were prepared byheating together tall oil pitch, Tallene, and a polyoxyethylatednonylphenol surfactant at about 135 C. for approximately 2 /2 hours.Tallene contains 35-50% fatty acids; 24-32% resin acids; 22-32% sterols,higher alcohols, etc.; a softening point between 88-l08 R; an acidnumber between -75; and a saponification number between 90-110. Thereaction product, without any separation or purification, was used asthe additive. Table I shows the ratio of tall oil pitch to surfactantemployed in each of 4 additive preparations.

TABLE I Ester additive: Reactants 1 50 parts tall oil pitch and parts pnonylphenoxypoly(ethyleneoxy)ethanol wherein 21:50. parts tall oil pitchand 1 part p nonylphenoxypoly(ethyleneoxy)ethanol wherein n=30. partstall oil pitch and 1 part p nonylphenoxypoly(ethyleneoxy)ethanol whereinn=30. parts tall oil pitch and 5 parts pnonylphenoxypoly(ethyleneoxy)ethanol wherein n=9.

Drilling fluids of various compositions were made up, and each of theester additives in Table I was tested as a fluid loss control agent bythe method of API Recommended Practice, Standard Procedure for TestingDrilling Fluids, API RP 13B, first edition, November 1962, section 3,Filtration, Low Temperature Test, pages 8 and 9. In each instance thefluid loss was determined on the fresh drilling fluid afterincorporation of the fluid loss control additive and also onadditive-containing drilling fluid which had aged for 16 hours at 80 C.Each drilling fluid without ester additive was used in a control test.The drilling fluid compositions and test results are summarized in TableII.

Diesel oil, cc 15 --....IIIIIIII Fluid loss, ce.Fresh drilling fluidsFluid loss, cc.Drilling fluids aged 16 hours at 80 C.

Base drilling fluid (control). 47. 0 47. 0 47. 0 12. 0 30. 0 143. 0 143.0 Drilling fluid-l-additive 1- 84. 0 11. 4 5. 0 7. 2 6. 0 9. 8 14. 6Drilling fluid-l-additive 2- 64. 0 44. 0 14. 6 0. 2 10. 4 140. 0 150. 0Drilling fluid+additive 3 85. 0 15. 4 6. 7 7. 2 11. 7 35. 0 26. 0Drilling fluid+additive 4 115. 0 28. 2 8. 8 9. 8 33. 0 67. 0 72. 0

1 ygeight of additive expressed in grams represents pounds of additiveper barrel of drilling 2 Medium viscosity (regular) Driscose, sodiumcarboxymethylcellulose.

The results in Table II show that the ester additives in concentrationsgreater than 2 pounds per barrel of drilling fluid served as fluid losscontrol agents. In general, the reduction in the quantity of fluid lostfrom the drilling fluid was especially great in the drilling fluidcontaining salt or salt and gypsum.

EXAMPLE II Tall oil pitch esters were prepared by heating the reactantsas described in Example I to 270 C. while bubbling CO through themixture to remove water formed by the reaction. In this manner thereaction time could be reduced to about 1 hour. Esterification appearedto progress rapidly at about 250 C. Esters were also prepared wherein asolvent such as xylene was used to reduced the viscosity of the mixture.

Ester additive No. 5 was prepared by heating 104 parts by weight of talloil pitch and 140 parts by weight of EXAMPLE III Ester additives 5 and 6were added to aqueous drilling fluids containing an illitic claymarketed as P-95 clay and the treated drilling fluids were tested as inExample I. The results are shown in Table IH:

TABLE III [Fluid loss in 251b./bbl. P-95 drilling fluid] 30 minute waterloss aged 16 hours at 80 0.

Treatment, lb.lbbl 3 Ester #5 28 5. 2 3. 2 1. 8

l Solvent-free basis, assuming no efiect for the solvent.

The above results demonstrate the water loss control achieved with theesters prepared at the higher temperature.

EXAMPLE IV An aqueous drilling fluid containing 20 weight percent kaolinand 4 weight percent bentonite was treated with ester #1. The propertiesof the drilling fluid and the results of the treatment are shown in thefollowing Table TABLE IV.-FLOOOULATION OF BENTONITE Treatment, IbJbblPlastic viscosity, cp

0 3 23 Too thick to stir A 1 weight percent slurry of bentonite wasprepared and treated with about 1 lb./bbl. of ester #1. The bentonitewas substantially completely precipitated.

EXAMPLE V A Bentone-oil concentrate was prepared in a colloid millcontaining the following materials:

TABLE V Concentrate formulation #1 Parts by weight Diesel oil 1200Bentone 121 Sulfonated asphalt 50 Acetone 24 The mixture was milled toviscous liquid state. The mill will not handle a grease. The addition of60 to 100 parts by weight of an ester of the invention with millingproduces a concentrate having the consistency of a grease.

A drilling fluid was prepared according to the recipe of Table VI.

TABLE VI Drilling fluid #1 Parts by weight Diesel oil 200 Formulation #1I50 Ester #6 20 After mixing for 30 minutes drilling fluid #1 was testedand 200 parts by weight of barite weighting material was added, followedby 30 minutes mixing. The weighted drilling fluid was tested. Resultsare shown in Table VII.

A drilling fluid designated as drilling fluid #2 was prepared withoutusing a dispersion agent and colloid mill so as to compare with drillingfluid #1 in composition.

TABLE VII Drilling fluid #2- Parts by weight Diesel oil 332 Bentone 13.1Sulfonated asphalt 5.5 Ester #6 20 Drilling fluid #2 was mixed for 30minutes and tested Then 200 parts by weight of barite was added andafter mixing for 30 minutes the fluid was tested again. Results areshown in Table VIII.

TABLE VIE-COMPARISON 0F PREDISPERSED BEN- TONE-OIL DRILLING FLUID WITHCONVENTIONAL BENTONE-OIL FLUID Ops. Lbs/ ft.

Apparent Plastic Yield Initial 10 minute Drilling Fluid viscosityviscosity point gel gel #1 13 8 9 7 11 #1 +13 arite 21 14 13 9 13 9 5 76 6 #2-l-Barite 21 17 7 6 7 The 30-minute fluid loss from #1 weightedwith barite was 6.4 cc. whereas the fluid loss from #2 weighted withbarite was 11.4 cc.

The results above show that a drilling fluid prepared from theconcentrate is superior to a drilling fluid prepared from the variouscomponents at the well site in the properties of viscosity, gel strengthand fluid loss.

EXAMPLE VI A diesel oil-Bentone mixture containing about 2 weightpercent Bentone was used in the preparation of drilling fluids forsuspending barite weighting material.

TABLE IX Parts by weight Oil-Bentone mixture 450 Sulfonated asphalt 15Barite 200 The above drilling fluid will not suspend barite.

TABLE X Parts by weight Oil-Bentone mixture 430 Sulfonated asphalt 15Tall oil pitch ester #6 20 Barite 200 The above drilling fluid suspendedbarite satisfactorily.

The 30 minute fluid (oil) loss was 12 cc.

TABLE XI Parts by weight Oil-Bentone mixture 430 Sulfonated asphalt 15Tall oil pitch ester #6 20 Zinc stearate 5 Barite 200 The above drillingfluid suspended barite satisfactorily. The 30 minute fluid loss was 10.7cc. The zinc stearate reduced fluid loss. The addition of 5 parts byweight of California (Coalinga) asbestos to the above drilling fluidincreased the 30 minute fluid loss to 12.4 cc.

7 TABLE XH Parts by weight Oil-Bentone mixture 195 Diesel oil 195 Talloil pitch ester #7 1 23 California (Coalinga) asbestos 10 Barite 100Ester additive #7 was prepared by heating equal parts by weight of talloil pitch and p-nonylphenoxypoly(ethylene- Xy)ethanol wherein 11,:O inxylene. The product contained 59 weight percent ester.

The above drilling fluid suspended barite satisfactorily and had a 30minute fluid loss of 34.5 cc.

I have found that 2 parts by weight of tall oil pitch should be reactedwith from 1 to 6 or more parts by weight of polyoxyethylene compound forbest results in water loss control; however, beneficial results areobtained when the reactants are utilized in proportions outside thisrange. The reaction conditions of the example are satisfactory but theseconditions are not critical and simple routine experimentation willdetermine the optimum conditions for each ester.

I have found that esters prepard from tall oil and polyoxyethylenecompounds do not provide any appreciable amount of water loss control,particularly in drilling fluids containing substantial amounts of saltor gypsum.

The esters of the invention do not change appreciably the viscosity andgel strength of the drilling fluid.

That which is claimed is:

1. A concentrate for use in preparing oil base drilling muds consistingessentially of organophilic bentonitic clay; a sufficient amount ofhydrocarbon oil to form a grease; and an amount, sufficient to dispersesaid clay in said oil of the reaction product obtained by heating to atemperature in the range of about 130 to about 280 C. for about 1 to 3hours at atmospheric pressure a mixture of tall oil pitch and apolyoxyethylene compound having the formula R(OCH CH OH wherein n is aninteger of 4 to 500, R contains 0 to 60 carbon atoms and is selectedfrom the groupconsisting of hydrogen and alkyl, aryl, alkaryl, aralkyl,cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, and acyl radicals.

2. In a process for drilling a well with well drilling tools wherein adrilling fluid selected from the group consisting of a water basedrilling fluid containing illitic clay and oil base drilling fluidscontaining organophilic bentonitic clay is circulated in the well, themethod of decreasing the fluid loss through the mud sheath formed on thewall of the well which comprises incorporating in said drilling fluidabout 2 to 30 pounds per barrel of drilling fluid of an additiveconsisting essentially of the reaction product obtained by heating to atemperature in the range of about 130 to about 280 C. for about 1 to 3hours at atmospheric pressure a mixture of tall oil pitch and apolyoxyethylene compound having the formula R(-OCH CH OH wherein n is aninteger of 4 to 500, R contains 0 to carbon atoms and is selected fromthe group consisting of hydrogen and alkyl, aryl, alkaryl, aralkyl,cycloalkyl, cycloalkylalkyl, alkylcycloalkyl and acyl radicals; andcontacting the wall of the well with drilling fluid containing saidadditive.

3. The process of claim 2 wherein the drilling fluid is water basedrilling fluid containing illitic clay.

4. The process of claim 2 wherein the drilling fluid is an oil basedrilling fluid containing organophilic bentonitic clay.

5. The process of claim 2 wherein the drilling fluid is a water basedrilling fluid containing illitic clay and the drilling fluid iscontaminated with bentonitic clay.

References Cited UNITED STATES PATENTS 2,531,812 11/1950 Hauser 252-8.52,921,028 1/1960 Stratton 252-49.7 2,627,514 2/ 1953 Kirkpatrick et a1.260-97.5 2,675,353 4/1954 Dawson 252- 2,950,272 8/1960 Kirkpatrick eta1. 260-104 3,236,769 2/1966 Burdyn et a1. 252-85 3,238,164 3/1966 Speck260-97.5 X

HERBERT B. GUYNN, Primary Examiner US. Cl. X.R.

